Basically as solar rapidly drops off at sunset conventional is having trouble ramping up to meet demand.
On the other hand, wind power in many of the best sites peaks strongly in exactly the "duck head" period.
The reason is the "lake effect": Land heats and cools far more rapidly than bodies of water (which are nearly a constant temperature on a daily cycle). The difference forms a heat engine, and the cycle lags the solar cycle by several hours. In the afternoon and evening (peaking about sunset) the wind blows strongly from the water to the land. (In the morning it blows from the land to the water though more weakly.)
The wind power available through a given swept cross-section goes up with the CUBE of the wind speed: (The energy per unit mass goes up with the square of the velocity, and the amount of mass flowing goes with the first power, multiplying one more factor of v.) That means a doubling of the wind speed multiplies the availabe power bya factor of 8, a tripling by 27, and so on. So it doesn't take much variation in wind speed to create a large variation in power.
Some of the best sites to take advantage of this are on the western temperate-zone coasts of continents (which happen to contain a lot of the urban load.) There the lake effect is extreme, combining with the prevailig winds.
One of the most extreme examples is California's Altamont Pass, where a break in the mountains funnels the prevailing, westerlies combined with the lake effect winds - with the Pacific Ocean as the "lake" and CA's Central Valley as the "land". The area is practically paved with windmills.
But you don't need something that extreme. My NV place, in the eastern Sierra foothills, gets strong afternoon winds from the Nevada Desert working against the damp forests of the Sierras.
Even without a strong lake effect to "chop off the duck's head", wind and solar power complement each other and reasonably match demand in several other ways in areas where both are available. For a lot of sites with intermittent sun-blocking weather, the climate is such that the cloudy times are windy and the calm times sunny. (Wind may be more prevalent in winter, as well.) Sun power closely tracks the solar input component of air-conditioning load, while wind goes up (though more steeply) with heat gain/loss across insulation and via air infiltration. So with a combo of wind and solar energy harvesting, when the weather hands you more load it also hands you more power to handle it.